As many as 3 million Americans have or will have an enlarged thoracic aorta in the setting of a bicuspid aortic valve, even when valve function is normal. Progressive dilatation and aortic dissection may result with catastrophic consequences. Medical therapy is sometimes adopted to attenuate the progressive enlargement, but has never been tested in clinical trials. The best pharmacologic candidates are beta blockers or angiotensin receptor blockers, mainly based on emerging experience in other vascular conditions affecting the aorta. Research is needed to determine whether either strategy is superior to no treatment. The ideal study would be a randomized clinical trial testing the pragmatic effectiveness of the various treatment options, although such a trial requires adequate pilot data for proper planning. We hypothesize that superiority of one approach can be demonstrated. In order to obtain the necessary pilot data and experience for a future trial, we propose this feasibility protocol with the specific aim to: 1) quantify the prevalence of eligible patients for a future trial from all bicuspid valve patients seen at participating medical centers and surrounding clinics, 2) determine prescribing habits and patient compliance with various treatment strategies currently employed, and 3) quantify variance of change in aortic area over time for the target population. This limited three year feasibility study will gather information o all patients with a bicuspid aortic valve, from which eligible patients will be followed prospectively, including 60 patients undergoing serial MRI over 22-24 months to measure change in aortic area.